1. What is Conception Date Calculation?

The conception date is estimated by subtracting 266 days from the due date. This calculation is based on the typical 38-week (266-day) gestation period from conception to birth.

2. How Does the Calculator Work?

The calculator uses the simple formula:

Where:

• Due Date — The estimated date of delivery
• 266 days — The average duration of pregnancy from conception

Explanation: This calculation assumes a standard 38-week pregnancy from conception to birth (as opposed to 40 weeks from the last menstrual period).

3. Importance of Conception Date

Details: Knowing the conception date can help in understanding fetal development timelines and is sometimes used in fertility treatments or paternity cases.

4. Using the Calculator

Tips: Enter the due date in the format YYYY-MM-DD or use the date picker. The calculator will estimate when conception likely occurred.

5. Frequently Asked Questions (FAQ)

Q1: Why 266 days specifically?
A: 266 days represents 38 weeks, which is the average time from conception to birth. The more commonly cited 40 weeks includes the time since the last menstrual period.

Q2: How accurate is this calculation?
A: This provides an estimate. Actual conception dates can vary as pregnancy duration varies naturally between 37-42 weeks.

Q3: What if I know my last menstrual period instead?
A: Use an LMP-based calculator instead, which adds 280 days (40 weeks) to the first day of your last period.

Q4: Does this work for IVF pregnancies?
A: For IVF, the exact conception date is known, so this calculator isn't needed.

Q5: Can this determine paternity?
A: While it can estimate conception timing, paternity requires DNA testing as the fertile window spans several days.